After several years of testing and development, the Cosworth CS600 series High Performance Subaru EJ25 long block has arrived. The CS600 series is designed for extreme track day use and the demanding performance enthusiast. Each assembly is precision built by one of Cosworths skilled craftsmen using the finest components from our parts catalog to ensure maximum reliable power and performance. Starting with a new Subaru EJ257 semi closed deck block, we meticulously hone each bore to guarantee perfect piston to cylinder wall clearance. The block is then assembled with our Forged Pistons, motorsport grade Forged H Beam connecting rods along with our high performance rod and main bearings and a new STI Forged crankshaft. For maximum performance, an optional steel billet crank is available (CS600X). Once the cylinder block assembly is completed, we install a pair of our CNC machine port-bored Big Valve Cylinder heads with our proven S2 camshafts complete with valve lash set to our specifications. The cylinder heads are secured with our high performance 11mm steel studs and sealed with multi layer steel head gaskets. Finally, we install one of our blue-printed, high pressure oil pumps for maximum lubrication. This proven engine combination has been used by top teams to win events in both North America and Europe.
 
Specifications:

• New Subaru EJ25 STI Engine case
• New Subaru EJ25 STI Forged Crankshaft 79mm
• Cosworth Forged H-beam Connecting Rods
• Cosworth Forged Pistons 99.5mm (8.2:1)
• Cosworth motorsport Tri-metal bearings
• Balanced to within .5 gram
• Complete blue-print assembly
• Enlarged Intake and Exhaust ports
• Large diameter stainless steel intake valves
• Large diameter Inconel exhaust valves
• Hi Rev, Dual valve springs
• Titanium Retainers
• Hardened Steel spring platforms
• Multi angle valve job
• CNC Machined port finish
• Knife edge port divider
• Cosworth S2 High lift camshafts
• Valve lash set
• Cosworth high pressure oil pump
• Cam covers
• Cosworth serial number